a(1) = 1, a(2) = 21, a(n) = 77*a(n-2) for n>=3.

A182754

a(1) = 1, a(2) = 21, a(n) = 77*a(n-2) for n>=3.

Terms

    a(0) =1a(1) =21a(2) =77a(3) =1617a(4) =5929a(5) =124509a(6) =456533a(7) =9587193a(8) =35153041a(9) =738213861a(10) =2706784157a(11) =56842467297a(12) =208422380089

External references